The Peromyscus Genetic Stock Center (PGSC) provides a reliable source of disease free peromyscines, and is unmatched for the variety of Peromyscus species and mutants available. The PGSC provides animals for a variety of fields, including human infectious disease, behavioral studies, physiological adaptation, and genetic studies. Two developments should further enhance the interest in Peromyscus as an experimental organism. The NHGRI has selected, based on our submission of a white paper, to do a 6X sequence of one species and 2X sequence of 3 other species. This project is just underway at Baylor Medical College. In collaboration with Dr. Glenn (U. Georgia) a request was made to JGI/DOE for construction and sequencing of 50,000 Peromyscus EST clones. The EST clones have been made and quality assessments completed. This complete sequence data should be available within approximately one month. In addition, a first generation linkage map has revealed closer linkage relationships between Peromysus and Rattus than Peromyscus and Mus. Further linkage and chromosome painting analysis has allowed the construction of a linkage map that is chromosome based. These resources will enhance the importance of Peromyscus as a research tool in areas of gene discovery in the area of repetitive movement disorders, juvenile and adult ataxia, and epilepsy, gene expression in disease and environmental toxicology, and mechanisms of genomic imprinting, Peromyscus is a reservoir for two emerging infectious microorganisms. Hanta virus causes a disease with 40 percent mortality and is a potential bioterrorism agent. The causative agent of Lyme disease is also harbored in Peromyscus and nearly 15,000 cases occur annually. PGSC has provided animals for investigators studying these and other diseases such as Ehrlichiosis, babesiosis and plaque. The research aspect of the project is to continue the development of embryo cryopreservation methods and re- derivation of living animals in order to preserve rare mutants and germplasm for future use when needed and to decrease costs. Progress has been in obtaining an increase in embryo production using modifications of the hormonal treatment regimes used in mice. Embryos have been successfully frozen and thawed to undergo cell division. Future work will further refine these methods with the goal of re-derivation of living animals from frozen embryos.